This invention relates generally to the testing of electromagnetic radiation transmission and more particularly, but not by way of limitation, to a window transmittance tester for testing the amount of infrared radiation transmitted through a window.
Infrared imaging systems are utilized by the military for various mission functions. In addition, there are various infrared imaging systems available for commercial applications. For military aircraft, special windows are necessary to provide the required optical and mechanical performance. The special characteristics and sizes of these windows make them generally very expensive. The surfces and therefore the optical characteristics of the windows are affected by weather and particle erosion and electro-chemical reactions of the window coatings with air pollutants. Therefore, a periodic check of the window transmission is an important consideration to insure satisfactory performance of the windows and timely replacement if and when required.
At the present time, the only method of determining satisfactory window performance is through the use of large and difficult-to-use test equipment in laboratories. There is no satisfactory field equipment for checking window transmission prior to the subject invention.